According to French scientists 'trans-fats' may increase a woman's risk of breast cancer.
Trans fats are currently being phased out of food in many countries because they clog arteries and increase the risk of heart disease.
Scientists at the national scientific research center at the University of Paris in France, discovered the link between trans-fats and breast cancer after carrying out a study of women taking part in a large European cancer trial.
The team found that women with the highest blood levels of trans-fats had about twice the risk of breast cancer compared to women with the lowest levels.
Dr. Veronique Chajes says at this stage, they can only recommend limiting the consumption of processed foods, which is the main source of industrially produced trans-fatty acid.
Trans-fatty acids or trans-fats are produced by creating artificially hardened fats as in partial hydrogenization processes and were originally intended to be healthier substitutes for saturated fats such as butter and lard.
They are widely used in processed foods to give food texture, added flavour and a long shelf life.
New York and California have banned trans-fats in restaurant foods and Canada and Britain are considering following suit; many food companies have eliminated them from their products.
Dr. Chajes and her team examined blood samples collected between 1995 and 1998 from 25,000 women who had volunteered to report on their eating and lifestyle habits and then be tracked for years to see if they developed cancer.
They then studied 363 of the women who were later diagnosed with breast cancer and compared their blood levels of fatty acids with those of women without cancer.
They discovered that the higher the levels of trans-fatty acids, the more likely a woman was to have cancer; these women were in fact twice as likely to develop breast cancer than those with the lowest levels.